1. Technical Field
Example embodiments relate to semiconductor memory devices, and more particularly to nonvolatile memory devices and methods of programming nonvolatile memory devices.
2. Description of the Related Art
Semiconductor memory devices can be roughly divided into two categories according to whether they retain stored data when disconnected from power. These categories include volatile memory devices, which lose stored data when disconnected from power, and nonvolatile memory devices, which retain stored data when disconnected from power. Memory cells of a nonvolatile memory device, such as a flash memory device, may be classified into single level cells (SLCs) that store one bit of data per memory cell and multi-level cells (MLCs) that store more than one bit of data per memory cell.
To ensure accurate storage of the multi-bit data, the threshold voltage distributions of the MLCs must be separated by adequate sensing margins. However, certain aspects of newer flash memory devices, such as increasing integration density, may cause the threshold voltage distributions to widen due to electrical coupling between adjacent memory cells or a programming disturbance.